Case structure for electronic control device

ABSTRACT

Depending on the orientation by which a breathing filter is mounted in a vehicle, water can accumulate in the breathing filter, and prevent the pressure difference between the space inside a case and the outside air from being adjusted; therefore, the vehicular layout is limited. Also, because the filter is formed in the center of the case, electronic parts cannot be installed on substrates on the upper and lower surfaces of the filter, meaning that the substrate size and the case size will increase. In addition, the costs will increase. The structure of the present invention is characterized in that breathing paths are provided on the surfaces sandwiching a portion where a filter film is welded in the corner of a resin-side case of a vehicle-mounted electronic control device such as an engine control unit or an automatic transmission control unit, and in that the breathing paths are connected inside.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/038,608, filed May 23, 2016, which is a U. S. National Stageof PCT/JP2014/079901, filed on Nov. 12, 2014, and claims priority toJapanese Patent Application no. 2013-251608, filed Dec. 5, 2013. Thedisclosures of the prior applications are incorporated by referenceherein in their entirety.

TECHNICAL FIELD

The present invention relates to a case structure for an electroniccontrol device mounted on a vehicle, such as an engine control unit oran automatic transmission control unit, which has a waterproof structureprovided with a breathing filter.

BACKGROUND ART

An electronic control device, such as an engine control unit or anautomatic transmission control unit, which is mounted under a conditionwhere the unit is directly splashed with liquid such as water, forexample, mounted in an engine room, is configured to have a circuitboard mounted with electronic parts housed in a protective space(waterproofed space) in a case made up of a plurality of case partsjoined. In such an electronic control device, completely sealing a casecauses stress to be applied to a harness connected to a connectorportion and a waterproof portion at the tip of the harness due to apressure difference between the inside of the case and the outside air,resulting in making liquid such as water be liable to be drawn into theunit. Therefore, a structure has been provided in which a breathing pathis provided at a part of a case member and a breathing filter filmhaving permeability and waterproofness is attached to an end surface ofthe breathing path (e.g. PTL 1).

CITATION LIST Patent Literature

PTL 1: JP 2006-49618 A

SUMMARY OF INVENTION Technical Problem

However, in a conventional structure of an electronic control device,depending on a direction in which the device is mounted on a vehicle,water stays in a breathing filter portion to disable adjustment of apressure difference between the inside of a case and the outside air,resulting in limiting a vehicular layout. Additionally, since a filterportion is formed in the central part within the case, no electronicpart can be mounted on boards below and above the filter portion,resulting in increasing a board size and a case size. Additionally, acost-up problem is also involved.

Therefore, an object of the present invention is to provide anelectronic control equipment less limited than a conventional equipmentin terms of an equipment mounting direction.

Solution to Problem

The above-described problem is solved by the invention recited inClaims.

For example, breathing paths are provided in surfaces that sandwich apart to which a filter film is welded at a corner portion of aresin-side case of an electronic control device, and these paths areconnected to each other inside the case.

Advantageous Effects of Invention

The present invention enables provision of an electronic controlequipment less limited than a conventional equipment in terms of anequipment mounting direction.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an external view, and an expanded view and sectional viewsof a relevant part of an electronic control device according to Example1.

FIG. 2 shows an expanded view and a sectional view of a relevant part ina filter portion according to Example 2.

FIG. 3 shows an expanded view and a sectional view of a relevant part ina filter portion according to Example 2.

FIG. 4 shows an expanded view and a sectional view of a relevant part ina filter portion according to Example 4.

FIG. 5 shows an expanded view and sectional views of a relevant part ina filter portion according to Example 5.

FIG. 6 shows an external view, and an expanded view and a sectional viewof a relevant part of an electronic control device according to Example6.

FIG. 7 shows an expanded view and sectional views of a relevant part ina filter portion according to Example 7.

FIG. 8 shows expanded views and a sectional view of a relevant part in afilter portion according to Example 8.

FIG. 9 shows expanded views and a sectional view of a relevant part in afilter portion according to Example 9.

FIG. 10 is a sectional view showing that in a configuration including ametal cover and a resin base, an electronic part and the like can bemounted above a filter portion.

FIG. 11 is a sectional view showing that in a configuration including aresin cover and a metal base, an electronic part and the like can bemounted above a filter portion.

DESCRIPTION OF EMBODIMENTS

In the following, Examples of the present invention will be describedwith reference to FIG. 1 to FIG. 4. FIG. 1 shows an external view anddeveloped views of an electronic control device mounted on a vehicle,such as an engine control unit or an automatic transmission controlunit, which adopts a structure of the present Example. A view on arrow Ais an expanded view of a filter portion seen from the outside, thefilter portion being provided at a corner portion of a resin base.Additionally, the sectional views show sections of parts taken alongline B-B, line C-C and line D-D, respectively. FIG. 2 to FIG. 5 areexpanded views of filter portions seen from the outside, the filterportions having configurations different from each other. FIG. 6 showsan example of an electronic control device having a configurationincluding a metal base and a resin cover, and shows views of aconfiguration in which the resin cover is provided with a filterportion.

A view on arrow J is an expanded view of a filter portion seen from theoutside, the filter portion being provided at a corner portion of theresin cover. The sectional view is a part of the section taken alongline K-K. FIG. 7 to FIG. 9 are expanded views of filter portions seenfrom the outside, the filter portions having configurations differentfrom each other. FIG. 10 and FIG. 11 are sectional views showing theeffect of the present invention that parts can be mounted also on aboard below a filter portion.

Embodiment 1

FIG. 1 shows First Example of the present invention.

In the present Example, between an electronic part 4 a mounted on acircuit board 4 and a metal cover 2 (die-cast), a heat conductivematerial 4 b is interposed, and the circuit board 4 is fixed to themetal cover 2 by a circuit board fixing screw 6. For maintainingwaterproofness of a case, with an adhesive 5 interposed among aconnector for external connection 1, the metal cover 2 and a resin base3, the metal cover 2 and the resin base 3 are joined at heat caulkingportions 3 a obtained by thermally molding bosses provided at cornerparts of the resin base 3. The metal cover 2 and the resin base 3 may bejoined by other method such as using a screw or a rivet. At a cornerportion of the resin base 3, a breathing filter film 7 is provided. Thefilter may be provided at any corner portion. Methods of attaching thefilter film 7 to the resin base 3 include heat-welding, bonding with anadhesive, adhesion by an adhesive tape, integral molding with the resinbase 3, and the like. Breathing paths 8 are opened in surfacessandwiching a filter portion at the corner portion (breathing pathopening surfaces 9) and are connected to each other inside. Below thefilter film 7, a breathing hole 11 is provided to communicate with thebreathing path 8. In this case, an attachment position of the filterfilm 7 is set based on a positional relationship between the breathingpath 8 and the breathing hole 11 so as not to be seen from the outsidein order to prevent high pressure water from splashing the filter film7. Since the filter film 7 and the breathing path 8 are thin relative toa thickness of the case, the filter portion can be configured to be thinas a whole. Therefore, as shown in FIG. 10, a clearance with the circuitboard 4 can be made large to enable the electronic part 4 a to bemounted above the filter portion.

Embodiment 2

FIG. 2 shows Second Example of the present invention. As compared withthe above Example 1, at least one rib 10 is formed in a breathing path 8in order to ensure strength. It is necessary to provide the rib 10because as an opening area of the breathing path 8 is increased, thestrength of the filter portion is decreased. In addition to ensuring thestrength, the rib 10 serves also as a protective wall for preventinghigh pressure water from splashing a filter film 7. Similarly to Example1, since the filter portion has a small thickness, parts can be mountedalso on the board above the filter portion.

Embodiment 3

FIG. 3 shows Third Example of the present invention. As compared withthe above Example 2, a rib has a different shape. Similarly to Example1, the filter has a small thickness to enable parts to be mounted alsoon the board above the filter portion. Additionally, an opening area ofa breathing path 8 of a resin base 3 is decreased to suppress an inflowof high pressure water. Further, since a rib 10 is angled, the force ofinflowing high pressure water, which hits against a wall surface, isdispersed to reduce a pressure applied to a breathing filter film 7.

Embodiment 4

FIG. 4 shows Fourth Example of the present invention. As compared withthe above Examples 1 to 3, the insides of breathing paths formed inrespective surfaces sandwiching a filter portion are angled to crosswith each other within a base in order to improve drainability.Similarly to Example 1 to Example 3, the filter has a small thickness toenable parts to be mounted also on a board above the filter portion.Additionally, having an angle 12 facilitates discharging of enteringhigh pressure water at whichever angle the electronic control device ofthe present invention is arranged.

Embodiment 5

FIG. 5 shows Fifth Example of the present invention. As compared withthe above Example 1 to Example 4, a bottom surface of a breathing pathof a resin base 2 has a slanting portion 13 in order to improvedrainability. In this case, a filter film 7 is set based on a positionalrelationship between breathing paths 8 and a breathing hole 11 so as notto be seen from the outside in order to prevent high pressure water fromsplashing the filter film 7. Similarly to Example 1 to Example 4, thefilter portion has a small thickness to enable parts to be mounted alsoon a board above the filter portion.

Embodiment 6

FIG. 6 shows Sixth Example of the present invention. As compared withthe above Example 1, a resin cover 14 and a metal base 15 are used. Inthe present Example, between an electronic part 4 a mounted on a circuitboard 4 and the metal base 3, a heat conductive material 4 b isinterposed, and the circuit board 4 is fixed to the metal base 15 by acircuit board fixing screw 6. For maintaining waterproofness of a case,with an adhesive 5 interposed among a connector for external connection1, the resin cover 14 and the metal base 15, the cover and the base arejoined by heat caulking bosses provided at the four corners of the resincover 14. The resin cover 14 and the metal base 15 may be fixed by othermethod such as using a screw or a rivet. In this case, at the cornerportion of the resin cover 14, a filter film 7 is provided. The filtermay be provided at any corner portion. Methods of attaching the filterfilm 7 to the resin cover 14 include heat-welding, bonding with anadhesive, adhesion by an adhesive tape, integral molding with the resincover 14, and the like. Breathing paths 8 are opened in surfacessandwiching a filter portion at the corner portion and are connected toeach other inside. Below the filter film 7, a breathing hole 11 isprovided to communicate with the breathing path 8. In this case, thefilter film 7 is set based on a positional relationship between thebreathing path 8 and the breathing hole 11 so as not to be seen from theoutside in order to prevent high pressure water from splashing thefilter film 7. Since the filter film 7 and the breathing path 8 are thinrelative to a thickness of the case, the filter portion can beconfigured to be thin. Therefore, as shown in FIG. 11, a clearance withthe circuit board 4 can be made large to enable the electronic part 4 ato be mounted below the filter portion.

Embodiment 7

FIG. 7 shows Seventh Example of the present invention. As compared withthe above Example 6, a first breathing path 8 a is opened from a resincover upper surface 14 a toward a metal base 15, a second breathing path8 b is opened in a resin cover side surface 14 b so as to beperpendicular to the first path, and both paths cross with each otherwithin a resin cover 14. A breathing hole 11 is formed at a position atwhich the first and second breathing paths cross with each other andwhich is on the inner side of the resin cover 14, and further inside, abreathing filter film 7 is provided. In this case, the filter film 7 isset based on a positional relationship between the first and secondbreathing paths 8 a and 8 b and the breathing hole 11 so as not to beseen from the outside in order to prevent high pressure water fromsplashing the filter film 7. Similarly to Example 6, since the filterportion has a small thickness, parts can be mounted below the filterportion and on the board as well.

Embodiment 8

FIG. 8 shows Eighth Example of the present invention. As compared withthe above Example 6, in order to improve drainability, at a resin coverupper surface corner portion 14 c, breathing paths 8 are provided in aresin cover upper surface 14 a and a resin cover side surface 14 b andcross with each other within a resin cover 14. The breathing path 8 anda breathing hole 11 cross with each other and a breathing filter film 7is provided below the breathing hole 11. In this case, the filter film 7is set based on a positional relationship with the breathing path 8 soas not to be seen from the outside in order to prevent high pressurewater from splashing the filter film 7. Similarly to Example 6, since afilter portion has a small thickness, parts can be mounted below thefilter portion and on the board as well.

Embodiment 9

FIG. 9 shows Ninth Example of the present invention. As compared withthe above Example 8, in order to improve drainability, at a resin coverupper surface corner portion 14 c, a first breathing path 8 a is formedfrom a resin cover upper surface 14 a toward a metal base 15 and asecond breathing path 8 b is formed from the outer side of a resin coverside surface 14 b toward an inner side of a resin cover 14 so as tocross with each other within the resin base 14. The breathing paths 8 aand 8 b further cross with a breathing hole 11. A breathing filter film7 is provided on an inner side of the breathing hole 11 within the resincover 14. In this case, the filter film 7 is set based on a positionalrelationship with the breathing path 8 so as not to be seen from theoutside in order to prevent high pressure water from splashing thefilter film 7. Similarly to Example 6, a filter portion has a smallthickness to enable parts to be mounted below the filter portion and onthe board as well.

As described in the foregoing, according the present Examples, sincewater is unlikely to stay in an electronic control equipmentirrespectively of a direction, flexibility of layout for mounting theequipment on a vehicle can be increased. Additionally, since arrangementof the filter portion at the case corner portion ensures a clearancebetween the filter portion and the board, aboard fixing structure suchas a screw, and an electronic part can be arranged to enable an effectof preventing an increase in a board size to be obtained.

REFERENCE SIGNS LIST

-   1 connector for external connection-   2 metal cover-   3 resin base-   3 a heat caulking portion-   4 circuit board-   4 a electronic part-   4 b heat conductive material-   5 adhesive-   6 circuit board fixing screw-   7 breathing filter film-   8 breathing path-   8 a first breathing path-   8 b second breathing path-   9 breathing path opening surface-   10 rib-   11 breathing hole-   12 angle-   13 slanting portion-   14 resin cover-   14 a resin cover upper surface-   14 b resin cover side surface-   14 c resin cover upper surface corner portion-   15 metal base

The invention claimed is:
 1. An electronic control device comprising: acircuit board mounted with an electronic part; a case covering thecircuit board; and a filter film disposed between the inside and theoutside of the case, wherein: the case includes a base portion adaptedto have the circuit board mounted thereon, and a rectangular coverportion covering the circuit board, the cover portion includes an uppersurface portion, a plurality of side surface portions connecting to theupper surface portion, and a corner portion surrounded by the uppersurface portion and two of the side surface portions, each of the two ofthe side surface portions has an opening, a path that communicates withthe opening of each of the two of the side surface portions is providedwithin the case, the path connecting to the filter film, and the filterfilm is provided at the corner portion and is arranged at an angle withrespect to the upper surface portion.
 2. The electronic control deviceaccording to claim 1, wherein the opening has a trapezoidal shape. 3.The electronic control device according to claim 2, wherein the cover isformed of resin, and the base portion is formed of metal.
 4. Theelectronic control device according to claim 1, wherein the cover isformed of resin, and the base portion is formed of metal.
 5. Theelectronic control device according to claim 1, wherein the filter filmis provided such that it is not visible from an outside of the case.